Capacitor start motors require a method to extract speed data from the voltage across the motor start winding. By comparing the start winding RPM-sensitive voltage with the main AC input voltage (which serves as a reference voltage), the switch determines when the start circuit should be energized. The electronic switch interrupts the start circuit current after the motor has accelerated to the cut out speed, and reconnects the start circuit whenever the motor speed has fallen to cut in speed (usually about 50% of synchronous motor speed).

1. Electrically Protected: Designed to filter out electrical noise, so there is no concern of random switch malfunction.

6. Universal Design 50/60 Hz operation. Will work on 2, 4 or 6 pole motors of any manufacturer. Reduced inventory.

7. Line Voltage Compensation: No modifications or changes are required for line voltage variations. SINPAC Switches will operate in areas susceptible to brownouts or low voltage due to long wiring runs. It also means there will be less stress on the starting capacitor due to over voltage.

Motor HP ratings are typical. For an accurate selection procedure, measure start capacitor current during a normal start or at locked rotor and select a SINPAC Switch with higher maximum current rating than that measured.

3. Selection can be based on actual measurement of start capacitor current or two times the motor nameplate FLA rating.

4. Switch current rating must match or exceed the motor start capacitor current requirements. Always select a SINPAC Switch with the next higher current rating for:
a) High cycling applications.
b) Long acceleration time.
c) High ambients: Greater than 55° C.

5. To assure proper motor operation, the voltage across the start winding must reach the SINPAC Switch cut out reference voltage between 70% to 85% of motors synchronous speed.
Caution: SINPAC Switches are line voltage compensated. Changes in the line voltage will not affect system operation unless an overload condition causes reduced running speed, along with reduced voltage across the start winding.

6. Higher current switches can be used in place of lower rated switches of the same series.

Line Voltage Compensation Charts

Induced voltage across the start winding is directly proportional to motor speed and line voltage. All SINPAC Switches use this voltage to switch the start capacitor out of the circuit. Your motor with a SINPAC Switch must generate a voltage that is 20% greater than the switch cut out voltage to assure cut out of the start capacitor. Refer to charts above.